Valve train and method for reducing oil flow to deactivated engine valves

Abstract

An engine valve train has oil flow to valve actuating components cut off or restricted when the valves are closed, to reduce parasitic losses. In an exemplary embodiment, a pushrod has a pivotable connection with a valve actuating rocker arm through which internal oil passages conduct oil for lubricating the rocker arm. The passages are aligned during valve actuation but become misaligned when the valve is closed. Misalignment of the passages at the sliding connection reduces the amount of oil flow through the connection to improve engine efficiency. When applied to cylinder deactivation engines, oil flow to rocker arms of deactivated valves is completely cut off, or reduced, further reducing parasitic losses.

What is claimed is:  
     
       1. A valve train for an internal combustion engine, the valve train comprising; 
       a cam having a base circle and a lobe extending from the base circle;  
       a cam follower engaging the cam for reciprocation in a guide; and  
       a rocker arm operably engaged by the cam follower at a pivotable connection operative to pivot the rocker arm for opening and closing a valve;  
       the pivotable connection including lubrication passages which are aligned for lubricant flow from the cam follower to the rocker arm when the rocker arm is pivoted in a valve opening direction, the passages being at least partially misaligned when the rocker arm is in a valve closed position for limiting lubricant flow to the rocker arm when the valve is closed;  
       the cam follower being a switching hydraulic valve lifter capable of being deactivated so that the valve remains closed during engine operation and oil flow to the rocker arm in the valve closed position is at least substantially reduced.  
     
     
       2. A valve train as in  claim 1  wherein a lubrication supply opening in a generally reciprocable component communicates with an inlet opening in the rocker arm, the communication being such that the openings are aligned during valve actuation and become misaligned when the valve is closed. 
     
     
       3. A valve train as in  claim 1  wherein the pivotable connection is a spherical end and a socket. 
     
     
       4. A valve train as in  claim 1  including a pushrod between the cam follower and the rocker arm wherein the pivotable connection is between the pushrod and the rocker arm. 
     
     
       5. A valve train as in  claim 1  wherein misalignment of the passages in the pivotable connection stops the flow of lubrication to the rocker arm. 
     
     
       6. A valve train as in  claim 1  wherein lubrication flow to the rocker arm is substantially cut off when the valve is closed.